The invention relates to a method of manufacturing an optical fiber comprising a coating of a metal, in which method a fibre which consists of a synthetic resin at least on its outer circumference, is provided with an electrically conductive layer, after which a metal coating is electro-plated on it.
Optical fibers comprising a primary coating of a synthetic resin and a coating of a metal contiguous with the primary coating are known per se. Such metal coatings are provided on optical glass fibers so as to protect the optical fiber from water and water vapour.
It has already been suggested to coat an optical glass fiber comprising a primary coating of a synthetic resin with a mixture of a powder of an electrically conductive material and a polymer and to provide thereon a coating of a metal by electro-plating. In this method, the conductive layer must be dried before the metal layer is provided (See abstract of JP Kokai 57-124308). A layer of a mixture of an electrically conductive material and a polymer by nature has a comparatively high electrical resistance. As a result during electro-plating, the current density must be chosen to be comparatively low because otherwise too much thermal energy is generated in the conductive layer. This known method hence is not so suitable for a continuous process, because high speed electro-plating is not very well possible. Another disadvantage is that the process is carried out in two steps which can hardly be linked to a single continuous process. Under these conditions another problem is that a comparatively thick conductive layer is difficult to provide concentrically.